I have been power-watching all the films in the series this week. The series overall is not very good, and feels like I accidentally summoned Pinhead and the hell he brought for me was being forced to watch all his movies. Besides the first film, I took a strange liking to the 6th installment, Hellseeker, with Dean Winters (Law & Order, Allstate commercials, 30 Rock). There was even a Hellraiser video game movie! The most disappointing thing was that the monster designs, effects, and general creepy factor was done rather well, but the stories within them felt like mind-numbing interstices to the good stuff. It's a shame that such a creepy main villain is part of a not-so-great franchise. Even the cheesier slashers, I feel, had more entertainment value.
I heard there was a new one in the works, somewhere out there, if it gets out of development hell.